define("gallery/underscore/1.5.2/underscore-debug", [], function(require, exports, module) {
    //     Underscore.js 1.5.2
    //     http://underscorejs.org
    //     (c) 2009-2013 Jeremy Ashkenas, DocumentCloud and Investigative Reporters & Editors
    //     Underscore may be freely distributed under the MIT license.
    (function() {
        // Baseline setup
        // --------------
        // Establish the root object, `window` in the browser, or `exports` on the server.
        var root = this;
        // Save the previous value of the `_` variable.
        var previousUnderscore = root._;
        // Establish the object that gets returned to break out of a loop iteration.
        var breaker = {};
        // Save bytes in the minified (but not gzipped) version:
        var ArrayProto = Array.prototype, ObjProto = Object.prototype, FuncProto = Function.prototype;
        // Create quick reference variables for speed access to core prototypes.
        var push = ArrayProto.push, slice = ArrayProto.slice, concat = ArrayProto.concat, toString = ObjProto.toString, hasOwnProperty = ObjProto.hasOwnProperty;
        // All **ECMAScript 5** native function implementations that we hope to use
        // are declared here.
        var nativeForEach = ArrayProto.forEach, nativeMap = ArrayProto.map, nativeReduce = ArrayProto.reduce, nativeReduceRight = ArrayProto.reduceRight, nativeFilter = ArrayProto.filter, nativeEvery = ArrayProto.every, nativeSome = ArrayProto.some, nativeIndexOf = ArrayProto.indexOf, nativeLastIndexOf = ArrayProto.lastIndexOf, nativeIsArray = Array.isArray, nativeKeys = Object.keys, nativeBind = FuncProto.bind;
        // Create a safe reference to the Underscore object for use below.
        var _ = function(obj) {
            if (obj instanceof _) return obj;
            if (!(this instanceof _)) return new _(obj);
            this._wrapped = obj;
        };
        // Export the Underscore object for **Node.js**, with
        // backwards-compatibility for the old `require()` API. If we're in
        // the browser, add `_` as a global object via a string identifier,
        // for Closure Compiler "advanced" mode.
        if (typeof exports !== "undefined") {
            if (typeof module !== "undefined" && module.exports) {
                exports = module.exports = _;
            }
            exports._ = _;
        } else {
            root._ = _;
        }
        // Current version.
        _.VERSION = "1.5.2";
        // Collection Functions
        // --------------------
        // The cornerstone, an `each` implementation, aka `forEach`.
        // Handles objects with the built-in `forEach`, arrays, and raw objects.
        // Delegates to **ECMAScript 5**'s native `forEach` if available.
        var each = _.each = _.forEach = function(obj, iterator, context) {
            if (obj == null) return;
            if (nativeForEach && obj.forEach === nativeForEach) {
                obj.forEach(iterator, context);
            } else if (obj.length === +obj.length) {
                for (var i = 0, length = obj.length; i < length; i++) {
                    if (iterator.call(context, obj[i], i, obj) === breaker) return;
                }
            } else {
                var keys = _.keys(obj);
                for (var i = 0, length = keys.length; i < length; i++) {
                    if (iterator.call(context, obj[keys[i]], keys[i], obj) === breaker) return;
                }
            }
        };
        // Return the results of applying the iterator to each element.
        // Delegates to **ECMAScript 5**'s native `map` if available.
        _.map = _.collect = function(obj, iterator, context) {
            var results = [];
            if (obj == null) return results;
            if (nativeMap && obj.map === nativeMap) return obj.map(iterator, context);
            each(obj, function(value, index, list) {
                results.push(iterator.call(context, value, index, list));
            });
            return results;
        };
        var reduceError = "Reduce of empty array with no initial value";
        // **Reduce** builds up a single result from a list of values, aka `inject`,
        // or `foldl`. Delegates to **ECMAScript 5**'s native `reduce` if available.
        _.reduce = _.foldl = _.inject = function(obj, iterator, memo, context) {
            var initial = arguments.length > 2;
            if (obj == null) obj = [];
            if (nativeReduce && obj.reduce === nativeReduce) {
                if (context) iterator = _.bind(iterator, context);
                return initial ? obj.reduce(iterator, memo) : obj.reduce(iterator);
            }
            each(obj, function(value, index, list) {
                if (!initial) {
                    memo = value;
                    initial = true;
                } else {
                    memo = iterator.call(context, memo, value, index, list);
                }
            });
            if (!initial) throw new TypeError(reduceError);
            return memo;
        };
        // The right-associative version of reduce, also known as `foldr`.
        // Delegates to **ECMAScript 5**'s native `reduceRight` if available.
        _.reduceRight = _.foldr = function(obj, iterator, memo, context) {
            var initial = arguments.length > 2;
            if (obj == null) obj = [];
            if (nativeReduceRight && obj.reduceRight === nativeReduceRight) {
                if (context) iterator = _.bind(iterator, context);
                return initial ? obj.reduceRight(iterator, memo) : obj.reduceRight(iterator);
            }
            var length = obj.length;
            if (length !== +length) {
                var keys = _.keys(obj);
                length = keys.length;
            }
            each(obj, function(value, index, list) {
                index = keys ? keys[--length] : --length;
                if (!initial) {
                    memo = obj[index];
                    initial = true;
                } else {
                    memo = iterator.call(context, memo, obj[index], index, list);
                }
            });
            if (!initial) throw new TypeError(reduceError);
            return memo;
        };
        // Return the first value which passes a truth test. Aliased as `detect`.
        _.find = _.detect = function(obj, iterator, context) {
            var result;
            any(obj, function(value, index, list) {
                if (iterator.call(context, value, index, list)) {
                    result = value;
                    return true;
                }
            });
            return result;
        };
        // Return all the elements that pass a truth test.
        // Delegates to **ECMAScript 5**'s native `filter` if available.
        // Aliased as `select`.
        _.filter = _.select = function(obj, iterator, context) {
            var results = [];
            if (obj == null) return results;
            if (nativeFilter && obj.filter === nativeFilter) return obj.filter(iterator, context);
            each(obj, function(value, index, list) {
                if (iterator.call(context, value, index, list)) results.push(value);
            });
            return results;
        };
        // Return all the elements for which a truth test fails.
        _.reject = function(obj, iterator, context) {
            return _.filter(obj, function(value, index, list) {
                return !iterator.call(context, value, index, list);
            }, context);
        };
        // Determine whether all of the elements match a truth test.
        // Delegates to **ECMAScript 5**'s native `every` if available.
        // Aliased as `all`.
        _.every = _.all = function(obj, iterator, context) {
            iterator || (iterator = _.identity);
            var result = true;
            if (obj == null) return result;
            if (nativeEvery && obj.every === nativeEvery) return obj.every(iterator, context);
            each(obj, function(value, index, list) {
                if (!(result = result && iterator.call(context, value, index, list))) return breaker;
            });
            return !!result;
        };
        // Determine if at least one element in the object matches a truth test.
        // Delegates to **ECMAScript 5**'s native `some` if available.
        // Aliased as `any`.
        var any = _.some = _.any = function(obj, iterator, context) {
            iterator || (iterator = _.identity);
            var result = false;
            if (obj == null) return result;
            if (nativeSome && obj.some === nativeSome) return obj.some(iterator, context);
            each(obj, function(value, index, list) {
                if (result || (result = iterator.call(context, value, index, list))) return breaker;
            });
            return !!result;
        };
        // Determine if the array or object contains a given value (using `===`).
        // Aliased as `include`.
        _.contains = _.include = function(obj, target) {
            if (obj == null) return false;
            if (nativeIndexOf && obj.indexOf === nativeIndexOf) return obj.indexOf(target) != -1;
            return any(obj, function(value) {
                return value === target;
            });
        };
        // Invoke a method (with arguments) on every item in a collection.
        _.invoke = function(obj, method) {
            var args = slice.call(arguments, 2);
            var isFunc = _.isFunction(method);
            return _.map(obj, function(value) {
                return (isFunc ? method : value[method]).apply(value, args);
            });
        };
        // Convenience version of a common use case of `map`: fetching a property.
        _.pluck = function(obj, key) {
            return _.map(obj, function(value) {
                return value[key];
            });
        };
        // Convenience version of a common use case of `filter`: selecting only objects
        // containing specific `key:value` pairs.
        _.where = function(obj, attrs, first) {
            if (_.isEmpty(attrs)) return first ? void 0 : [];
            return _[first ? "find" : "filter"](obj, function(value) {
                for (var key in attrs) {
                    if (attrs[key] !== value[key]) return false;
                }
                return true;
            });
        };
        // Convenience version of a common use case of `find`: getting the first object
        // containing specific `key:value` pairs.
        _.findWhere = function(obj, attrs) {
            return _.where(obj, attrs, true);
        };
        // Return the maximum element or (element-based computation).
        // Can't optimize arrays of integers longer than 65,535 elements.
        // See [WebKit Bug 80797](https://bugs.webkit.org/show_bug.cgi?id=80797)
        _.max = function(obj, iterator, context) {
            if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
                return Math.max.apply(Math, obj);
            }
            if (!iterator && _.isEmpty(obj)) return -Infinity;
            var result = {
                computed: -Infinity,
                value: -Infinity
            };
            each(obj, function(value, index, list) {
                var computed = iterator ? iterator.call(context, value, index, list) : value;
                computed > result.computed && (result = {
                    value: value,
                    computed: computed
                });
            });
            return result.value;
        };
        // Return the minimum element (or element-based computation).
        _.min = function(obj, iterator, context) {
            if (!iterator && _.isArray(obj) && obj[0] === +obj[0] && obj.length < 65535) {
                return Math.min.apply(Math, obj);
            }
            if (!iterator && _.isEmpty(obj)) return Infinity;
            var result = {
                computed: Infinity,
                value: Infinity
            };
            each(obj, function(value, index, list) {
                var computed = iterator ? iterator.call(context, value, index, list) : value;
                computed < result.computed && (result = {
                    value: value,
                    computed: computed
                });
            });
            return result.value;
        };
        // Shuffle an array, using the modern version of the 
        // [Fisher-Yates shuffle](http://en.wikipedia.org/wiki/Fisher–Yates_shuffle).
        _.shuffle = function(obj) {
            var rand;
            var index = 0;
            var shuffled = [];
            each(obj, function(value) {
                rand = _.random(index++);
                shuffled[index - 1] = shuffled[rand];
                shuffled[rand] = value;
            });
            return shuffled;
        };
        // Sample **n** random values from an array.
        // If **n** is not specified, returns a single random element from the array.
        // The internal `guard` argument allows it to work with `map`.
        _.sample = function(obj, n, guard) {
            if (arguments.length < 2 || guard) {
                return obj[_.random(obj.length - 1)];
            }
            return _.shuffle(obj).slice(0, Math.max(0, n));
        };
        // An internal function to generate lookup iterators.
        var lookupIterator = function(value) {
            return _.isFunction(value) ? value : function(obj) {
                return obj[value];
            };
        };
        // Sort the object's values by a criterion produced by an iterator.
        _.sortBy = function(obj, value, context) {
            var iterator = lookupIterator(value);
            return _.pluck(_.map(obj, function(value, index, list) {
                return {
                    value: value,
                    index: index,
                    criteria: iterator.call(context, value, index, list)
                };
            }).sort(function(left, right) {
                var a = left.criteria;
                var b = right.criteria;
                if (a !== b) {
                    if (a > b || a === void 0) return 1;
                    if (a < b || b === void 0) return -1;
                }
                return left.index - right.index;
            }), "value");
        };
        // An internal function used for aggregate "group by" operations.
        var group = function(behavior) {
            return function(obj, value, context) {
                var result = {};
                var iterator = value == null ? _.identity : lookupIterator(value);
                each(obj, function(value, index) {
                    var key = iterator.call(context, value, index, obj);
                    behavior(result, key, value);
                });
                return result;
            };
        };
        // Groups the object's values by a criterion. Pass either a string attribute
        // to group by, or a function that returns the criterion.
        _.groupBy = group(function(result, key, value) {
            (_.has(result, key) ? result[key] : result[key] = []).push(value);
        });
        // Indexes the object's values by a criterion, similar to `groupBy`, but for
        // when you know that your index values will be unique.
        _.indexBy = group(function(result, key, value) {
            result[key] = value;
        });
        // Counts instances of an object that group by a certain criterion. Pass
        // either a string attribute to count by, or a function that returns the
        // criterion.
        _.countBy = group(function(result, key) {
            _.has(result, key) ? result[key]++ : result[key] = 1;
        });
        // Use a comparator function to figure out the smallest index at which
        // an object should be inserted so as to maintain order. Uses binary search.
        _.sortedIndex = function(array, obj, iterator, context) {
            iterator = iterator == null ? _.identity : lookupIterator(iterator);
            var value = iterator.call(context, obj);
            var low = 0, high = array.length;
            while (low < high) {
                var mid = low + high >>> 1;
                iterator.call(context, array[mid]) < value ? low = mid + 1 : high = mid;
            }
            return low;
        };
        // Safely create a real, live array from anything iterable.
        _.toArray = function(obj) {
            if (!obj) return [];
            if (_.isArray(obj)) return slice.call(obj);
            if (obj.length === +obj.length) return _.map(obj, _.identity);
            return _.values(obj);
        };
        // Return the number of elements in an object.
        _.size = function(obj) {
            if (obj == null) return 0;
            return obj.length === +obj.length ? obj.length : _.keys(obj).length;
        };
        // Array Functions
        // ---------------
        // Get the first element of an array. Passing **n** will return the first N
        // values in the array. Aliased as `head` and `take`. The **guard** check
        // allows it to work with `_.map`.
        _.first = _.head = _.take = function(array, n, guard) {
            if (array == null) return void 0;
            return n == null || guard ? array[0] : slice.call(array, 0, n);
        };
        // Returns everything but the last entry of the array. Especially useful on
        // the arguments object. Passing **n** will return all the values in
        // the array, excluding the last N. The **guard** check allows it to work with
        // `_.map`.
        _.initial = function(array, n, guard) {
            return slice.call(array, 0, array.length - (n == null || guard ? 1 : n));
        };
        // Get the last element of an array. Passing **n** will return the last N
        // values in the array. The **guard** check allows it to work with `_.map`.
        _.last = function(array, n, guard) {
            if (array == null) return void 0;
            if (n == null || guard) {
                return array[array.length - 1];
            } else {
                return slice.call(array, Math.max(array.length - n, 0));
            }
        };
        // Returns everything but the first entry of the array. Aliased as `tail` and `drop`.
        // Especially useful on the arguments object. Passing an **n** will return
        // the rest N values in the array. The **guard**
        // check allows it to work with `_.map`.
        _.rest = _.tail = _.drop = function(array, n, guard) {
            return slice.call(array, n == null || guard ? 1 : n);
        };
        // Trim out all falsy values from an array.
        _.compact = function(array) {
            return _.filter(array, _.identity);
        };
        // Internal implementation of a recursive `flatten` function.
        var flatten = function(input, shallow, output) {
            if (shallow && _.every(input, _.isArray)) {
                return concat.apply(output, input);
            }
            each(input, function(value) {
                if (_.isArray(value) || _.isArguments(value)) {
                    shallow ? push.apply(output, value) : flatten(value, shallow, output);
                } else {
                    output.push(value);
                }
            });
            return output;
        };
        // Flatten out an array, either recursively (by default), or just one level.
        _.flatten = function(array, shallow) {
            return flatten(array, shallow, []);
        };
        // Return a version of the array that does not contain the specified value(s).
        _.without = function(array) {
            return _.difference(array, slice.call(arguments, 1));
        };
        // Produce a duplicate-free version of the array. If the array has already
        // been sorted, you have the option of using a faster algorithm.
        // Aliased as `unique`.
        _.uniq = _.unique = function(array, isSorted, iterator, context) {
            if (_.isFunction(isSorted)) {
                context = iterator;
                iterator = isSorted;
                isSorted = false;
            }
            var initial = iterator ? _.map(array, iterator, context) : array;
            var results = [];
            var seen = [];
            each(initial, function(value, index) {
                if (isSorted ? !index || seen[seen.length - 1] !== value : !_.contains(seen, value)) {
                    seen.push(value);
                    results.push(array[index]);
                }
            });
            return results;
        };
        // Produce an array that contains the union: each distinct element from all of
        // the passed-in arrays.
        _.union = function() {
            return _.uniq(_.flatten(arguments, true));
        };
        // Produce an array that contains every item shared between all the
        // passed-in arrays.
        _.intersection = function(array) {
            var rest = slice.call(arguments, 1);
            return _.filter(_.uniq(array), function(item) {
                return _.every(rest, function(other) {
                    return _.indexOf(other, item) >= 0;
                });
            });
        };
        // Take the difference between one array and a number of other arrays.
        // Only the elements present in just the first array will remain.
        _.difference = function(array) {
            var rest = concat.apply(ArrayProto, slice.call(arguments, 1));
            return _.filter(array, function(value) {
                return !_.contains(rest, value);
            });
        };
        // Zip together multiple lists into a single array -- elements that share
        // an index go together.
        _.zip = function() {
            var length = _.max(_.pluck(arguments, "length").concat(0));
            var results = new Array(length);
            for (var i = 0; i < length; i++) {
                results[i] = _.pluck(arguments, "" + i);
            }
            return results;
        };
        // Converts lists into objects. Pass either a single array of `[key, value]`
        // pairs, or two parallel arrays of the same length -- one of keys, and one of
        // the corresponding values.
        _.object = function(list, values) {
            if (list == null) return {};
            var result = {};
            for (var i = 0, length = list.length; i < length; i++) {
                if (values) {
                    result[list[i]] = values[i];
                } else {
                    result[list[i][0]] = list[i][1];
                }
            }
            return result;
        };
        // If the browser doesn't supply us with indexOf (I'm looking at you, **MSIE**),
        // we need this function. Return the position of the first occurrence of an
        // item in an array, or -1 if the item is not included in the array.
        // Delegates to **ECMAScript 5**'s native `indexOf` if available.
        // If the array is large and already in sort order, pass `true`
        // for **isSorted** to use binary search.
        _.indexOf = function(array, item, isSorted) {
            if (array == null) return -1;
            var i = 0, length = array.length;
            if (isSorted) {
                if (typeof isSorted == "number") {
                    i = isSorted < 0 ? Math.max(0, length + isSorted) : isSorted;
                } else {
                    i = _.sortedIndex(array, item);
                    return array[i] === item ? i : -1;
                }
            }
            if (nativeIndexOf && array.indexOf === nativeIndexOf) return array.indexOf(item, isSorted);
            for (;i < length; i++) if (array[i] === item) return i;
            return -1;
        };
        // Delegates to **ECMAScript 5**'s native `lastIndexOf` if available.
        _.lastIndexOf = function(array, item, from) {
            if (array == null) return -1;
            var hasIndex = from != null;
            if (nativeLastIndexOf && array.lastIndexOf === nativeLastIndexOf) {
                return hasIndex ? array.lastIndexOf(item, from) : array.lastIndexOf(item);
            }
            var i = hasIndex ? from : array.length;
            while (i--) if (array[i] === item) return i;
            return -1;
        };
        // Generate an integer Array containing an arithmetic progression. A port of
        // the native Python `range()` function. See
        // [the Python documentation](http://docs.python.org/library/functions.html#range).
        _.range = function(start, stop, step) {
            if (arguments.length <= 1) {
                stop = start || 0;
                start = 0;
            }
            step = arguments[2] || 1;
            var length = Math.max(Math.ceil((stop - start) / step), 0);
            var idx = 0;
            var range = new Array(length);
            while (idx < length) {
                range[idx++] = start;
                start += step;
            }
            return range;
        };
        // Function (ahem) Functions
        // ------------------
        // Reusable constructor function for prototype setting.
        var ctor = function() {};
        // Create a function bound to a given object (assigning `this`, and arguments,
        // optionally). Delegates to **ECMAScript 5**'s native `Function.bind` if
        // available.
        _.bind = function(func, context) {
            var args, bound;
            if (nativeBind && func.bind === nativeBind) return nativeBind.apply(func, slice.call(arguments, 1));
            if (!_.isFunction(func)) throw new TypeError();
            args = slice.call(arguments, 2);
            return bound = function() {
                if (!(this instanceof bound)) return func.apply(context, args.concat(slice.call(arguments)));
                ctor.prototype = func.prototype;
                var self = new ctor();
                ctor.prototype = null;
                var result = func.apply(self, args.concat(slice.call(arguments)));
                if (Object(result) === result) return result;
                return self;
            };
        };
        // Partially apply a function by creating a version that has had some of its
        // arguments pre-filled, without changing its dynamic `this` context.
        _.partial = function(func) {
            var args = slice.call(arguments, 1);
            return function() {
                return func.apply(this, args.concat(slice.call(arguments)));
            };
        };
        // Bind all of an object's methods to that object. Useful for ensuring that
        // all callbacks defined on an object belong to it.
        _.bindAll = function(obj) {
            var funcs = slice.call(arguments, 1);
            if (funcs.length === 0) throw new Error("bindAll must be passed function names");
            each(funcs, function(f) {
                obj[f] = _.bind(obj[f], obj);
            });
            return obj;
        };
        // Memoize an expensive function by storing its results.
        _.memoize = function(func, hasher) {
            var memo = {};
            hasher || (hasher = _.identity);
            return function() {
                var key = hasher.apply(this, arguments);
                return _.has(memo, key) ? memo[key] : memo[key] = func.apply(this, arguments);
            };
        };
        // Delays a function for the given number of milliseconds, and then calls
        // it with the arguments supplied.
        _.delay = function(func, wait) {
            var args = slice.call(arguments, 2);
            return setTimeout(function() {
                return func.apply(null, args);
            }, wait);
        };
        // Defers a function, scheduling it to run after the current call stack has
        // cleared.
        _.defer = function(func) {
            return _.delay.apply(_, [ func, 1 ].concat(slice.call(arguments, 1)));
        };
        // Returns a function, that, when invoked, will only be triggered at most once
        // during a given window of time. Normally, the throttled function will run
        // as much as it can, without ever going more than once per `wait` duration;
        // but if you'd like to disable the execution on the leading edge, pass
        // `{leading: false}`. To disable execution on the trailing edge, ditto.
        _.throttle = function(func, wait, options) {
            var context, args, result;
            var timeout = null;
            var previous = 0;
            options || (options = {});
            var later = function() {
                previous = options.leading === false ? 0 : new Date();
                timeout = null;
                result = func.apply(context, args);
            };
            return function() {
                var now = new Date();
                if (!previous && options.leading === false) previous = now;
                var remaining = wait - (now - previous);
                context = this;
                args = arguments;
                if (remaining <= 0) {
                    clearTimeout(timeout);
                    timeout = null;
                    previous = now;
                    result = func.apply(context, args);
                } else if (!timeout && options.trailing !== false) {
                    timeout = setTimeout(later, remaining);
                }
                return result;
            };
        };
        // Returns a function, that, as long as it continues to be invoked, will not
        // be triggered. The function will be called after it stops being called for
        // N milliseconds. If `immediate` is passed, trigger the function on the
        // leading edge, instead of the trailing.
        _.debounce = function(func, wait, immediate) {
            var timeout, args, context, timestamp, result;
            return function() {
                context = this;
                args = arguments;
                timestamp = new Date();
                var later = function() {
                    var last = new Date() - timestamp;
                    if (last < wait) {
                        timeout = setTimeout(later, wait - last);
                    } else {
                        timeout = null;
                        if (!immediate) result = func.apply(context, args);
                    }
                };
                var callNow = immediate && !timeout;
                if (!timeout) {
                    timeout = setTimeout(later, wait);
                }
                if (callNow) result = func.apply(context, args);
                return result;
            };
        };
        // Returns a function that will be executed at most one time, no matter how
        // often you call it. Useful for lazy initialization.
        _.once = function(func) {
            var ran = false, memo;
            return function() {
                if (ran) return memo;
                ran = true;
                memo = func.apply(this, arguments);
                func = null;
                return memo;
            };
        };
        // Returns the first function passed as an argument to the second,
        // allowing you to adjust arguments, run code before and after, and
        // conditionally execute the original function.
        _.wrap = function(func, wrapper) {
            return function() {
                var args = [ func ];
                push.apply(args, arguments);
                return wrapper.apply(this, args);
            };
        };
        // Returns a function that is the composition of a list of functions, each
        // consuming the return value of the function that follows.
        _.compose = function() {
            var funcs = arguments;
            return function() {
                var args = arguments;
                for (var i = funcs.length - 1; i >= 0; i--) {
                    args = [ funcs[i].apply(this, args) ];
                }
                return args[0];
            };
        };
        // Returns a function that will only be executed after being called N times.
        _.after = function(times, func) {
            return function() {
                if (--times < 1) {
                    return func.apply(this, arguments);
                }
            };
        };
        // Object Functions
        // ----------------
        // Retrieve the names of an object's properties.
        // Delegates to **ECMAScript 5**'s native `Object.keys`
        _.keys = nativeKeys || function(obj) {
            if (obj !== Object(obj)) throw new TypeError("Invalid object");
            var keys = [];
            for (var key in obj) if (_.has(obj, key)) keys.push(key);
            return keys;
        };
        // Retrieve the values of an object's properties.
        _.values = function(obj) {
            var keys = _.keys(obj);
            var length = keys.length;
            var values = new Array(length);
            for (var i = 0; i < length; i++) {
                values[i] = obj[keys[i]];
            }
            return values;
        };
        // Convert an object into a list of `[key, value]` pairs.
        _.pairs = function(obj) {
            var keys = _.keys(obj);
            var length = keys.length;
            var pairs = new Array(length);
            for (var i = 0; i < length; i++) {
                pairs[i] = [ keys[i], obj[keys[i]] ];
            }
            return pairs;
        };
        // Invert the keys and values of an object. The values must be serializable.
        _.invert = function(obj) {
            var result = {};
            var keys = _.keys(obj);
            for (var i = 0, length = keys.length; i < length; i++) {
                result[obj[keys[i]]] = keys[i];
            }
            return result;
        };
        // Return a sorted list of the function names available on the object.
        // Aliased as `methods`
        _.functions = _.methods = function(obj) {
            var names = [];
            for (var key in obj) {
                if (_.isFunction(obj[key])) names.push(key);
            }
            return names.sort();
        };
        // Extend a given object with all the properties in passed-in object(s).
        _.extend = function(obj) {
            each(slice.call(arguments, 1), function(source) {
                if (source) {
                    for (var prop in source) {
                        obj[prop] = source[prop];
                    }
                }
            });
            return obj;
        };
        // Return a copy of the object only containing the whitelisted properties.
        _.pick = function(obj) {
            var copy = {};
            var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
            each(keys, function(key) {
                if (key in obj) copy[key] = obj[key];
            });
            return copy;
        };
        // Return a copy of the object without the blacklisted properties.
        _.omit = function(obj) {
            var copy = {};
            var keys = concat.apply(ArrayProto, slice.call(arguments, 1));
            for (var key in obj) {
                if (!_.contains(keys, key)) copy[key] = obj[key];
            }
            return copy;
        };
        // Fill in a given object with default properties.
        _.defaults = function(obj) {
            each(slice.call(arguments, 1), function(source) {
                if (source) {
                    for (var prop in source) {
                        if (obj[prop] === void 0) obj[prop] = source[prop];
                    }
                }
            });
            return obj;
        };
        // Create a (shallow-cloned) duplicate of an object.
        _.clone = function(obj) {
            if (!_.isObject(obj)) return obj;
            return _.isArray(obj) ? obj.slice() : _.extend({}, obj);
        };
        // Invokes interceptor with the obj, and then returns obj.
        // The primary purpose of this method is to "tap into" a method chain, in
        // order to perform operations on intermediate results within the chain.
        _.tap = function(obj, interceptor) {
            interceptor(obj);
            return obj;
        };
        // Internal recursive comparison function for `isEqual`.
        var eq = function(a, b, aStack, bStack) {
            // Identical objects are equal. `0 === -0`, but they aren't identical.
            // See the [Harmony `egal` proposal](http://wiki.ecmascript.org/doku.php?id=harmony:egal).
            if (a === b) return a !== 0 || 1 / a == 1 / b;
            // A strict comparison is necessary because `null == undefined`.
            if (a == null || b == null) return a === b;
            // Unwrap any wrapped objects.
            if (a instanceof _) a = a._wrapped;
            if (b instanceof _) b = b._wrapped;
            // Compare `[[Class]]` names.
            var className = toString.call(a);
            if (className != toString.call(b)) return false;
            switch (className) {
              // Strings, numbers, dates, and booleans are compared by value.
                case "[object String]":
                // Primitives and their corresponding object wrappers are equivalent; thus, `"5"` is
                // equivalent to `new String("5")`.
                return a == String(b);

              case "[object Number]":
                // `NaN`s are equivalent, but non-reflexive. An `egal` comparison is performed for
                // other numeric values.
                return a != +a ? b != +b : a == 0 ? 1 / a == 1 / b : a == +b;

              case "[object Date]":
              case "[object Boolean]":
                // Coerce dates and booleans to numeric primitive values. Dates are compared by their
                // millisecond representations. Note that invalid dates with millisecond representations
                // of `NaN` are not equivalent.
                return +a == +b;

              // RegExps are compared by their source patterns and flags.
                case "[object RegExp]":
                return a.source == b.source && a.global == b.global && a.multiline == b.multiline && a.ignoreCase == b.ignoreCase;
            }
            if (typeof a != "object" || typeof b != "object") return false;
            // Assume equality for cyclic structures. The algorithm for detecting cyclic
            // structures is adapted from ES 5.1 section 15.12.3, abstract operation `JO`.
            var length = aStack.length;
            while (length--) {
                // Linear search. Performance is inversely proportional to the number of
                // unique nested structures.
                if (aStack[length] == a) return bStack[length] == b;
            }
            // Objects with different constructors are not equivalent, but `Object`s
            // from different frames are.
            var aCtor = a.constructor, bCtor = b.constructor;
            if (aCtor !== bCtor && !(_.isFunction(aCtor) && aCtor instanceof aCtor && _.isFunction(bCtor) && bCtor instanceof bCtor)) {
                return false;
            }
            // Add the first object to the stack of traversed objects.
            aStack.push(a);
            bStack.push(b);
            var size = 0, result = true;
            // Recursively compare objects and arrays.
            if (className == "[object Array]") {
                // Compare array lengths to determine if a deep comparison is necessary.
                size = a.length;
                result = size == b.length;
                if (result) {
                    // Deep compare the contents, ignoring non-numeric properties.
                    while (size--) {
                        if (!(result = eq(a[size], b[size], aStack, bStack))) break;
                    }
                }
            } else {
                // Deep compare objects.
                for (var key in a) {
                    if (_.has(a, key)) {
                        // Count the expected number of properties.
                        size++;
                        // Deep compare each member.
                        if (!(result = _.has(b, key) && eq(a[key], b[key], aStack, bStack))) break;
                    }
                }
                // Ensure that both objects contain the same number of properties.
                if (result) {
                    for (key in b) {
                        if (_.has(b, key) && !size--) break;
                    }
                    result = !size;
                }
            }
            // Remove the first object from the stack of traversed objects.
            aStack.pop();
            bStack.pop();
            return result;
        };
        // Perform a deep comparison to check if two objects are equal.
        _.isEqual = function(a, b) {
            return eq(a, b, [], []);
        };
        // Is a given array, string, or object empty?
        // An "empty" object has no enumerable own-properties.
        _.isEmpty = function(obj) {
            if (obj == null) return true;
            if (_.isArray(obj) || _.isString(obj)) return obj.length === 0;
            for (var key in obj) if (_.has(obj, key)) return false;
            return true;
        };
        // Is a given value a DOM element?
        _.isElement = function(obj) {
            return !!(obj && obj.nodeType === 1);
        };
        // Is a given value an array?
        // Delegates to ECMA5's native Array.isArray
        _.isArray = nativeIsArray || function(obj) {
            return toString.call(obj) == "[object Array]";
        };
        // Is a given variable an object?
        _.isObject = function(obj) {
            return obj === Object(obj);
        };
        // Add some isType methods: isArguments, isFunction, isString, isNumber, isDate, isRegExp.
        each([ "Arguments", "Function", "String", "Number", "Date", "RegExp" ], function(name) {
            _["is" + name] = function(obj) {
                return toString.call(obj) == "[object " + name + "]";
            };
        });
        // Define a fallback version of the method in browsers (ahem, IE), where
        // there isn't any inspectable "Arguments" type.
        if (!_.isArguments(arguments)) {
            _.isArguments = function(obj) {
                return !!(obj && _.has(obj, "callee"));
            };
        }
        // Optimize `isFunction` if appropriate.
        if (typeof /./ !== "function") {
            _.isFunction = function(obj) {
                return typeof obj === "function";
            };
        }
        // Is a given object a finite number?
        _.isFinite = function(obj) {
            return isFinite(obj) && !isNaN(parseFloat(obj));
        };
        // Is the given value `NaN`? (NaN is the only number which does not equal itself).
        _.isNaN = function(obj) {
            return _.isNumber(obj) && obj != +obj;
        };
        // Is a given value a boolean?
        _.isBoolean = function(obj) {
            return obj === true || obj === false || toString.call(obj) == "[object Boolean]";
        };
        // Is a given value equal to null?
        _.isNull = function(obj) {
            return obj === null;
        };
        // Is a given variable undefined?
        _.isUndefined = function(obj) {
            return obj === void 0;
        };
        // Shortcut function for checking if an object has a given property directly
        // on itself (in other words, not on a prototype).
        _.has = function(obj, key) {
            return hasOwnProperty.call(obj, key);
        };
        // Utility Functions
        // -----------------
        // Run Underscore.js in *noConflict* mode, returning the `_` variable to its
        // previous owner. Returns a reference to the Underscore object.
        _.noConflict = function() {
            root._ = previousUnderscore;
            return this;
        };
        // Keep the identity function around for default iterators.
        _.identity = function(value) {
            return value;
        };
        // Run a function **n** times.
        _.times = function(n, iterator, context) {
            var accum = Array(Math.max(0, n));
            for (var i = 0; i < n; i++) accum[i] = iterator.call(context, i);
            return accum;
        };
        // Return a random integer between min and max (inclusive).
        _.random = function(min, max) {
            if (max == null) {
                max = min;
                min = 0;
            }
            return min + Math.floor(Math.random() * (max - min + 1));
        };
        // List of HTML entities for escaping.
        var entityMap = {
            escape: {
                "&": "&amp;",
                "<": "&lt;",
                ">": "&gt;",
                '"': "&quot;",
                "'": "&#x27;"
            }
        };
        entityMap.unescape = _.invert(entityMap.escape);
        // Regexes containing the keys and values listed immediately above.
        var entityRegexes = {
            escape: new RegExp("[" + _.keys(entityMap.escape).join("") + "]", "g"),
            unescape: new RegExp("(" + _.keys(entityMap.unescape).join("|") + ")", "g")
        };
        // Functions for escaping and unescaping strings to/from HTML interpolation.
        _.each([ "escape", "unescape" ], function(method) {
            _[method] = function(string) {
                if (string == null) return "";
                return ("" + string).replace(entityRegexes[method], function(match) {
                    return entityMap[method][match];
                });
            };
        });
        // If the value of the named `property` is a function then invoke it with the
        // `object` as context; otherwise, return it.
        _.result = function(object, property) {
            if (object == null) return void 0;
            var value = object[property];
            return _.isFunction(value) ? value.call(object) : value;
        };
        // Add your own custom functions to the Underscore object.
        _.mixin = function(obj) {
            each(_.functions(obj), function(name) {
                var func = _[name] = obj[name];
                _.prototype[name] = function() {
                    var args = [ this._wrapped ];
                    push.apply(args, arguments);
                    return result.call(this, func.apply(_, args));
                };
            });
        };
        // Generate a unique integer id (unique within the entire client session).
        // Useful for temporary DOM ids.
        var idCounter = 0;
        _.uniqueId = function(prefix) {
            var id = ++idCounter + "";
            return prefix ? prefix + id : id;
        };
        // By default, Underscore uses ERB-style template delimiters, change the
        // following template settings to use alternative delimiters.
        _.templateSettings = {
            evaluate: /<%([\s\S]+?)%>/g,
            interpolate: /<%=([\s\S]+?)%>/g,
            escape: /<%-([\s\S]+?)%>/g
        };
        // When customizing `templateSettings`, if you don't want to define an
        // interpolation, evaluation or escaping regex, we need one that is
        // guaranteed not to match.
        var noMatch = /(.)^/;
        // Certain characters need to be escaped so that they can be put into a
        // string literal.
        var escapes = {
            "'": "'",
            "\\": "\\",
            "\r": "r",
            "\n": "n",
            "	": "t",
            "\u2028": "u2028",
            "\u2029": "u2029"
        };
        var escaper = /\\|'|\r|\n|\t|\u2028|\u2029/g;
        // JavaScript micro-templating, similar to John Resig's implementation.
        // Underscore templating handles arbitrary delimiters, preserves whitespace,
        // and correctly escapes quotes within interpolated code.
        _.template = function(text, data, settings) {
            var render;
            settings = _.defaults({}, settings, _.templateSettings);
            // Combine delimiters into one regular expression via alternation.
            var matcher = new RegExp([ (settings.escape || noMatch).source, (settings.interpolate || noMatch).source, (settings.evaluate || noMatch).source ].join("|") + "|$", "g");
            // Compile the template source, escaping string literals appropriately.
            var index = 0;
            var source = "__p+='";
            text.replace(matcher, function(match, escape, interpolate, evaluate, offset) {
                source += text.slice(index, offset).replace(escaper, function(match) {
                    return "\\" + escapes[match];
                });
                if (escape) {
                    source += "'+\n((__t=(" + escape + "))==null?'':_.escape(__t))+\n'";
                }
                if (interpolate) {
                    source += "'+\n((__t=(" + interpolate + "))==null?'':__t)+\n'";
                }
                if (evaluate) {
                    source += "';\n" + evaluate + "\n__p+='";
                }
                index = offset + match.length;
                return match;
            });
            source += "';\n";
            // If a variable is not specified, place data values in local scope.
            if (!settings.variable) source = "with(obj||{}){\n" + source + "}\n";
            source = "var __t,__p='',__j=Array.prototype.join," + "print=function(){__p+=__j.call(arguments,'');};\n" + source + "return __p;\n";
            try {
                render = new Function(settings.variable || "obj", "_", source);
            } catch (e) {
                e.source = source;
                throw e;
            }
            if (data) return render(data, _);
            var template = function(data) {
                return render.call(this, data, _);
            };
            // Provide the compiled function source as a convenience for precompilation.
            template.source = "function(" + (settings.variable || "obj") + "){\n" + source + "}";
            return template;
        };
        // Add a "chain" function, which will delegate to the wrapper.
        _.chain = function(obj) {
            return _(obj).chain();
        };
        // OOP
        // ---------------
        // If Underscore is called as a function, it returns a wrapped object that
        // can be used OO-style. This wrapper holds altered versions of all the
        // underscore functions. Wrapped objects may be chained.
        // Helper function to continue chaining intermediate results.
        var result = function(obj) {
            return this._chain ? _(obj).chain() : obj;
        };
        // Add all of the Underscore functions to the wrapper object.
        _.mixin(_);
        // Add all mutator Array functions to the wrapper.
        each([ "pop", "push", "reverse", "shift", "sort", "splice", "unshift" ], function(name) {
            var method = ArrayProto[name];
            _.prototype[name] = function() {
                var obj = this._wrapped;
                method.apply(obj, arguments);
                if ((name == "shift" || name == "splice") && obj.length === 0) delete obj[0];
                return result.call(this, obj);
            };
        });
        // Add all accessor Array functions to the wrapper.
        each([ "concat", "join", "slice" ], function(name) {
            var method = ArrayProto[name];
            _.prototype[name] = function() {
                return result.call(this, method.apply(this._wrapped, arguments));
            };
        });
        _.extend(_.prototype, {
            // Start chaining a wrapped Underscore object.
            chain: function() {
                this._chain = true;
                return this;
            },
            // Extracts the result from a wrapped and chained object.
            value: function() {
                return this._wrapped;
            }
        });
    }).call(this);
});
